It's got us all looking back on not just our past, but also the history of handhelds in general: how the formats through the ages have changed, and the watershed moments for devices that you can fit in your back pocket.

What better time, then, to put together a list of the greatest and most important portable systems the gaming world has ever seen.

We'll be choosing six handhelds to coincide with our sixth birthday, but we won't be counting the 3DS and Vita, as they haven't been around long enough for us to judge the enormity of their impact. However, every other format we cover - and even those we weren't around for - has a shot at the #1 spot.

So, which systems make the list? What takes the title of greatest handheld console ever made? Will the Tapwave Zodiac be a surprise entry on the list?

Read on to find out...

6. Sega Game Gear

The thinking over at Sega circa 1989 went something like this: we've got this technology lying around that's solid but getting a bit long in the tooth. We've managed to condense this tech - with a few compromises - into a smaller design, slap a screen on it, and effectively allow developers to make games for two systems at once (making ports much simpler to produce). This is all gonna make for a gaming experience very similar to the one offered by our ageing home console.

Sound familiar to a recently launched Sony device at all?

The Game Gear was years ahead of its time, with a full-colour screen on which you could watch television if you picked up the TV Tuner accessory. That made it, perhaps, the first multi-use portable. And through the use of the MasterGear Converter, it could run the entire back catalogue of Master System titles. Pretty nifty for a portable released in 1990, eh?

5. PlayStation Portable

It really is a brilliant bit of kit, the old PSP. Its visuals, for starters, outstripped those of its DS rival with ease. When the first screens sneaked out and its graphical grunt was demonstrated with WipEout Pure, people were flabbergasted.

As details of its low-cost media format, full-length movies on UMD, upgradable memory card functionality, and top-end sound capabilities emerged, it seemed that this would be the device to beat.

It wasn't to be, of course, but it was home to some excellent games and sold well enough - especially in Japan, due to the popularity of Monster Hunter. It also managed to change with the times to a certain degree. Sony embraced online gaming, bite-sized downloadable content, and multimedia content (including music streaming and digital comics) on the PSP long before its rivals did on their platforms.

4. Neo Geo Pocket Color

You might not have played, or even seen a Neo Geo Pocket Color in the wild, but you will have absolutely felt its impact on the world of portables.

The system was created in response to Nintendo's hogging of the handheld limelight for too long (by having long beaten off competition from Atari's Lynx and Sega's Game Gear). The Big N's now-ancient Game Boy was becoming a stale product, but no company was challenging it for market dominance.

SNK saw an opening and went for it with its Neo Geo Pocket and - shortly after - Neo Geo Pocket Color, which featured a sharp colour display, connectivity to the Dreamcast, super-precise arcade stick-like controls, and support from both Sega and Capcom.

It was cheap to buy, had great games, and could surely look forward to a bright future. This new competitor forced Nintendo to react swiftly by pushing hardware performance forward. So, Nintendo did, bringing the Game Boy Advance into the world, and in the process crushing the Neo Geo Pocket Color.

The Neo Geo Pocket Color failed, but before it disappeared, it showed that the king could be toppled - or, at least, made nervous at the prospect of competition in the marketplace.

3. Nintendo Game Boy

Well, it wouldn't be right to not include it somewhere on this list, right?

If you're not old enough to have owned one of these beauties, then you won't understand the impact the Game Boy had on how and when video game fans played. Nintendo's first portable with interchangeable cartridges was a revelation - a godsend for those that didn't want to stop playing just because they left the sofa.

Yes, the screen refresh rate was rubbish and it wasn't backlit for those secret "past bedtime" Super Mario Land sessions, but its battery life was stunning on just four AA batteries. Its myriad accessories, including a camera, printer, multiplayer link cable, and all-important magnifier with its own light source, more than made up for these drawbacks.

Gunpei Yokoi's decision to use older technology in new ways kept its manufacturing costs down, leading to mass adoption among younger players. This meant that pretty soon every kid at school had one. This laid the competitive yet social groundwork for a little game called Pokemon to come along and take the world by storm.

No other piece of hardware in the last two decades has shaken up the games industry like the iPhone.

The downloadable content-only model, along with a low barrier to entry for game makers to the App Store, propelled the independent dev scene forward in ways unimaginable prior to 2008. It wouldn't be an exaggeration to say that thousands of developers owe their livelihoods to Apple's 3.5-inch touchscreen slab.

Creativity on the iPhone has flourished due to the ease with which developers can reach a mass audience, with massive conglomerates and tiny two-person teams getting in on the action. The high-budget Infinity Blades and Dead Spaces nestle in rather comfortably among the more modestly funded Hard Lines and Tilt To Lives.

Apple's mobile marvel has also raised that sticky subject about how much we're prepared to pay for the medium we love again. Titles that rival those found on traditional portables are often put out at the oh-so-alluring price of 69p, as opposed to £30, forcing consumers to question exactly what they consider value for money to be. And if you don't think the old-guard publishers and platform-holders are utterly terrified by the freemium model that's enjoying so much success on iOS, you're playing on a different planet.

But, if you're still not convinced Apple's blower belongs here, just imagine for a moment that the iPhone hadn't supported games. When you got bored during your ten-minute bus ride last Tuesday, or during that coffee break at work, or when you waited in a queue at the shops, how would you have whiled away the time? Blankly stared out a nearby window at passers-by? Yep, probably.

1. Nintendo DS

It was perhaps inevitable that the company responsible for the incredible popularity of handhelds today would secure the top spot on our list. But, why the DS over any of Nintendo's other industry-leading devices?

Put plainly, the Nintendo DS is a massive success story: one that likely won't be repeated again in quite the same way. You can look at sales numbers for the various units produced, from the gloriously ugly original, to the sleek and stylish Lite, through to the fit in your handbag DSi and the gigantic XL. You can quote staggering software figures for the most popular titles, such as Mario Kart DS and the Pokemon releases. But, that's only a fraction of the story.

The vision for the DS was clear from the very beginning. Nintendo was after the biggest gaming audience of them all: non-gamers.

Before the DS, gaming was largely the pursuit of hobbyists, teenage boys, and children. Shortly after the "third pillar" of Nintendo's hardware portfolio saw daylight, you'd start to notice more diverse types of people gaming in public. This is thanks in part to the immediacy of interaction that the DS brought with it.

The stylus made the system more user-friendly for an audience that wasn't used to figuring out which combination of buttons resulted in what reaction from a player avatar. Simple things like item management in Animal Crossing were now a doddle, and even 'core' titles, such as the Zeldafranchise, made great use of this input method to improve its accessibility.

And when Nintendo was faced with the threat of simple-to-implement and rampant piracy on its platform - something Sony's PSP (the DS's nearest competitor) could not withstand - Ninty doused these flames by getting lawyers to ban R4 cards in most European countries. Its main tactic for overcoming the piracy problem that plagued the PSP, however, was in continuing to point publishers and developers in the direction of the phenomenal sales numbers for reassurance that they'd make money on the platform.

To the DS, then, goes the trophy. The greatest portable yet made. Its vast catalogue, incredible sales record, and the way its control systems changed the perspective of gamers - and non-gamers - the world over ensure that it takes home the title.